In the months or years after surgery, the lens capsule gradually ‘shrink wraps’ the IOL and stabilises it in its natural position. During this process the lens capsule may sometimes become cloudy, visual quality deteriorates and it can feel as if the cataract is coming back. The timing of this complication, called posterior capsular opacification (PCO) or secondary cataract is variable, but affected patients will typically notice deterioration in vision and problems with light scatter between 6 months and 6 years after surgery. PCO is corrected by cutting through the thin, frosted-over lens capsule to restore a clear pathway for light to focus on the retina. This is done with a YAG laser in a painless 2 minute corrective procedure known as YAG laser capsulotomy.  This normally restores vision to the level achieved within 24 hours of the original cataract surgery.

The risks associated with YAG laser capsulotomy are rare.

• IOL damage: correctable with an operation similar to cataract surgery, in which the damaged IOL is exchanged for a new one.
• In around 1% of cases (1 in 100 patients), the patient may experience a mild waterlogging or bruising response in the retina, known as cystoid macular oedema. This causes a usually temporary reduction of vision lasting, typically, 6-9 months. Approximately 1 in 400 patients will suffer retinal detachment. Some floaters (loose debris from the lens capsule, appearing like moving flies or cobwebs in the field of vision) are common after YAG capsulotomy. However, a sudden new shower of floaters, lightning flashes or a curtain-like loss of the visual field, are danger signs that a retinal detachment may be in progress.
• If you experience flashes, floaters or sudden visual loss after either cataract surgery or YAG capsulotomy, you should always go straight to a Casualty Department for an emergency eye examination.